Tillotson HL63B Carb tune question...

[crane]

I've aquired a McCulloch 1-40 saw. Re-set the points, air gap, new plug and did a quick strip and clean of the carb. Got her fired up and set and away we go.....BUT.... the saw really starts to bog and hesitate when under load. If I tickle her with a little choke, she comes right back. A few of you have told me that these old McCullochs are torque monsters...Mine is more like a puppy!
Now I read with great intrest GASoline"s rebuild pictorial and learned loads(adjusting the float plate, etc) I think(and it hurts) my problem may lie with the high idle mixture. Local shops all have different ideas on how to set this. Any ideas would help. I'm almost there, but need that last little tuning up to make her sing.

Drew

 

[PES+]

Try this

Richen your low speed screw and adjust the idle stop accordingly to get a good idle.

From what you are describing it sounds like your low speed adjustment is too lean

Where is your low speed needle now?

These carburetors are not 1 turn static adjust but are closer at 2 turns out low and 1 turn or 3/4 turn out high jet from lightly seated.

I have all the repair manuals and service bulletins but I cannot look up the static carburetor settings as these were in the owners manuals for each individual series of saw.

Maybe someone has an owners manual for the series

 

[crane]

thanks for the approx static settings. I'm definiately not a pro when it comes to carbs, but am willing to learn. The mechanic at the local shop told me to set "L" so the saw runs at the highest rpm back out needle ten minuites then adjust the idle govenor down to get you best idle speed??? This didn't make a lot of sense to me, but, like I said I'm not a pro. With the "H", adjust till you get the higest rpm with throttle wide open then back off ten minutes again. Let me know if this is all sounding way out there in left field. I just want to tune this saw, not wreck it!

Drew

 

[heimannm]

McCulloch tuning

If you have to tickle the choke, it is running too lean. Try opening the H jet by 10-15 minutes (15 minutes = 90°). I like to adjust mine to the point they just start to 4-cycle running wide open/unloaded.

If you get tired of messing with this saw, let me know. I don't have a 1-40 in the stable yet.

Mark

 

[crane]

Mark,
Thanks for the tip. I'm going to strip the carb down later today. Having troubles getting a carb kit locally,but will broaden my search. Just a quick question... can you explain what you mean when you say it starts to 4-cycle?? I've heard a few guys talk about this on site here.
If I can, I'll upload a pic of the saw. Almost all the original paint is intact and looking good. Was a saw someone thru in the loacal land fill. To get her to run all that was needed was to clean and adjust the points. One mans junk....

Drew

 

[heimannm]

4 cycle

When it is running lean it will really scream and turn high rev's, as you turn the H screw CCW it will begin to slow down a bit, and eventually start to miss, burble, or 4 cycle, called that because it is running so rich it misses every other cycle, making it a 4 stroke.

Hope that makes some sense to you. You don't want to run it too lean for very long or it will damage the piston and cylinder due to high heat and too little lubrication.

Mark